[POWERPC] PS3: Use __maybe_unused

Change the PS3 debug routines from using the GCC specific
'__attribute__ ((unused))' to the preprocessor macro
__maybe_unused.

Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
3 files changed